How to save DRY when using node-mongodb-native

Question

db.open(function(err,db){ //handle error db.collection("book",function(err, collection){ //handle error collection.doSomething1(... function(err, result){ //handle error collection.doSomething2(... function(err, result){ ... }) }) }) }) 

but we will not write db.open every time we want to do something, but we need to make sure that db opens when we use it.

we still won’t handle the error every time in the same code.

we can also reuse the collection.

similar

 errorHandledDB.doSomething1("book",... function(result){ errorHandledDB.doSomething2("book",...function(result){ ... }) }) 

Answer 1

Answer my question. Since there are no better options, I do it myself, I am starting a project to simplify it, check node-mongoskin .

Answer 2

I have implemented a server application using mongodb for logging. I implemented data access using some classes of providers, as shown in the example.

provider.filelog.js

 var Db= require('mongodb/db').Db, ObjectID= require('mongodb/bson/bson').ObjectID, Server= require('mongodb/connection').Server, log = require('lib/common').log; FilelogProvider = function (host, port, database) { this.db= new Db(database, new Server(host, port, {auto_reconnect: true}, {})); this.db.open(function(){}); }; FilelogProvider.prototype.getCollection= function(callback) { this.db.collection('filelogs', function(error, log_collection) { if (error) callback(error); else { log_collection.ensureIndex([[ 'created', 1 ]], false, function(err, indexName) { if (error) callback(error); callback(null, log_collection); }); } }); }; FilelogProvider.prototype.findAll = function(callback) { this.getCollection(function(error, log_collection) { if (error) callback(error); else { log_collection.find(function(error, cursor) { if (error) callback(error); else { cursor.toArray(function(error, results) { if (error) callback(error); else callback(null, results); }); } }); } }); }; 

Since I use Grasshopper as my http middleware, I can easily deploy providers using the DI functionality provided by gh:

server.js

 gh.addToContext({ providers: { filelog: new FilelogProvider(conf.mongodb_host, conf.mongodb_port, conf.mongodb_database), status: new ServerstatusProvider(conf.mongodb_host, conf.mongodb_port, conf.mongodb_database) }, log: log }); 

Access to suppliers in each controller function is now great:

 gh.get('/serve', function() { this.providers.filelog.findAll(function(err, res) { // access data here }); }); 

This implementation is pretty specific to Grasshopper (since it uses DI), but I think you get this idea. I also implemented the solution using express and mongoose, you will find here here . This solution is a little cleaner than using the native driver, as it provides models for use with the database.

Update

Just for the sake of it: if you really want to adhere to the DRY principle, stop doing ORM implementation and use Mongoose . If you need special features like Map / Reduce, you can still use your own driver (which Mongoose is built on).

Answer 3

I speak here theoretically, not to mention Mongo.

I would recommend you try to create such a package.

The level of data access, or at least the model, it all depends on your architecture and needs, and this is on your side.

Just wrap access to mongodb with a layer of abstract commands, than write an abstract model object, and all other model objects inherit from it, and automatically set all getters and setters for the attributes of the record you pulled from mongo db.

for an update, you simply give it a save method that iterates through and saves all changes made to it.

Since it is not relational, and I don’t know if this suits your design well, the model may not be useful here.

Hope this helps, Good luck!